Facial weakness did not develop in any patient who received a marginal dose of less than
15 Gy (163 patients).

Useful hearing in the affected ear means "testable speech
discrimination", defined as Gardner-Robertson grades 1 and 2, PTA (pure tone average)
at 0-50dB and SDS (speech discrimination score) at 50-100%; hearing levels
below that are not considered useful, and were not reported.

The tumor was measured by volume (cc's) rather than size (cm's).

Sources:

For Pittsburgh, 190 cases, 1992-97:Flickingeret al, "Results of acoustic neuroma radiosurgery: an
analysis of 5 years experience using current methods," Journal of Neurosurgery, vol94 (Jan 2001).